(1) Field of the Invention
The present invention relates to electromagnetic anechoic testing chambers, and more specifically to a method of converting an electromagnetic anechoic testing chamber to an electromagnetic complex cavity (or reverberation) testing chamber.
(2) Description of the Prior Art
Complex cavity radio frequency test techniques have been investigated for decades. These test techniques have been used to research real-world electromagnetic environments such as ship compartments, and have been integrated into compliance standards for electromagnetic compatibility, because of the robust nature of the testing and the strong correlation to real environments. The compliance testing utilizes a shielded, radio frequency reflective cavity to create a complex standing electromagnetic wave mode structure. The mode structure is “stirred” using one of a number of well-known methods, and the equipment being tested is subjected to a statistically known field over the course of the test. Presently, the testing chambers used for this compliance testing are constructed with the sole purpose of being used as reverberation chambers.
Electromagnetic compatibility standards also require radiated emissions and susceptibility testing to be performed in shielded anechoic chambers. These chambers are fully shielded from the outside electromagnetic environment and have radio frequency absorbing material placed on specific walls to reduce the amount of electromagnetic wave reflection within the chamber.
Due to the inherent nature of their respective designs, reverberation chambers cannot be substituted for anechoic chambers, and anechoic chambers cannot be substituted for reverberation chambers. Although both types of chambers are necessary for their respective testing purposes, it is rare for a single testing facility or research center to have both types of chambers due to the expense of constructing and maintaining them, as well as space limitations. There will be times when a facility that has an anechoic test chamber needs to perform complex cavity electromagnetic testing. What is needed in such a situation is a method to easily and temporarily convert an anechoic test chamber into a reverberation test chamber.